The present invention relates generally to a manner by which to communicate data, such as a vector graphic, in a bandwidth-constrained communication system. More particularly, the present invention relates to apparatus, and an associated method, by which to compress content, such as the vector graphic, at a sending station, prior to communication upon the bandwidth-constrained channel, to a receiving station. Further, the present invention relates to apparatus, and an associated method, by which to decompress the content, once received at a receiving station.
By compressing the content prior to its communication upon the communication channel, the bandwidth required to communicate the data is reduced. Data compression is great enough to permit communication of animated vector graphics, or other content, in a cellular, or other bandwidth-constrained, communication system.
A communication system operates to communicate data between a sending station and a receiving station. A communication channel connects the sending and receiving station together, and the data is communicated by the sending station upon the communication channel to the receiving station. If necessary, the data to be communicated by the sending station is converted into a form to permit its communication upon the communication channel. The informational content of the data is recovered, once communicated to the receiving station.
A large number of different types of communication systems have been developed and implemented to effectuate the communication of data between two or more sending and receiving stations.
A communication system is referred to as a radio communication system when the communication channel interconnecting the sending and receiving stations is defined upon a radio link extending therebetween. The radio link is defined upon a portion of the electromagnetic spectrum. Because a radio link is used upon which to define the communication channel rather than a wireline connection, a radio communication system is inherently mobile. A communication system that, instead, utilize a conventional wireline connection upon which to define the communication channel is typically of limited mobility due to the need to interconnect the sending and receiving stations by way of the conventional, wireline connections.
An exemplary type of radio communication system is a cellular communication system. Cellular communication systems have achieved wide levels of usage and have been installed throughout large geographical areas of the world. Successive generations of cellular communication systems have been developed and implemented. Succeeding ones of the generations of communication systems incorporate advancements in communication technologies.
Reference is commonly made to at least three generations of cellular communication systems. So-called, first-generation cellular communication systems were first-implemented and generally utilized analog modulation techniques. An AMPS (advanced mobile phone service) cellular communication system is exemplary of a first-generation cellular communication system. A so-called, second-generation cellular communication system typically refers to a cellular communication system that utilizes a digital, multiple-access communication scheme. Second-generation systems, in contrast to first-generation systems, generally offer higher-capacity systems that provide for at least low-rate data services. A GSM (global system for mobile communications), a TDMA (time-division, multiple-access) system, a PDC (Pacific digital cellular) system and a CDMA1 (code-division, multiple-access) system are all exemplary of second-generation, cellular communication systems. So-called, third-generation communication systems are presently being developed. Third-generation systems also utilize digital communication techniques and provide for different service classes of communication services. A WCDMA (wide band, code-division, multiple-access) system, an EDGE (enhanced data rate for GSM evolution) system, and a CDMA-2000 (code-division, multiple-access 2000) system are all exemplary of third-generation systems. And, successor-generation systems are additionally under development.
Cellular communication systems, as well as other types of communication systems, are bandwidth-constrained. That is to say, the bandwidth available upon which to define communication channels upon which to communicate data is limited. The limited availability of the bandwidth limits the amount of data that can be communicated during operation of the communication system. The only manner by which to increase the amount of data that can be communicated is to communicate the data more efficiently.
Compression, and corresponding decompression, techniques are proposed by which to compress the data into more efficient form prior to its communication upon a communication channel and, subsequently, to be decompressed to recover thereafter the informational content of the data.
While data that is to be communicated pursuant to new-generation cellular communication systems, as well as other types of communication systems, is representative of many different types of information, data forming vector graphics are exemplary of data that might need to be communicated pursuant to a communication session to effectuate a communication service. A vector graphic is data-intensive representation. A compression technique by which to compress a vector graphic, as well as other types of data, would advantageously facilitate improved communications in a cellular, or other, communication system.
It is in light of this background information related to the communication of data in a cellular radio, or other, communication system that the significant improvements of the present invention have evolved.
The present invention, accordingly, advantageously provides apparatus, and an associated method, by which to communicate data, such as a vector graphic, in a bandwidth-constrained communication system.
Through operation of an embodiment of the present invention, a manner is provided by which to compress content, such as a vector graphic, at a sending station prior to communication upon the bandwidth-constrained channel, to a receiving station. Also through operation of an embodiment of the present invention, a manner is provided by which to decompress the content once communicated to a receiving station.
The bandwidth required to communicate the data upon the communication channel is reduced as the content that is to be communicated is compressed prior to its communication upon the communication channel. When used in a data-intensive communication application, such as a multi-media communication session in which animated vector graphics are communicated, the amount of data required to be communicated upon the communication channel to effectuate the communication service is reduced. Data compression is great enough to permit communication of animated vector graphics, or other content, in a cellular radio communication system, or other bandwidth-constrained communication system in manners to permit communication of Internet-related information at acceptable throughput rates.
In one aspect of the present invention, a vector graphics representation is compressed prior to its communication upon a communication channel. The vector graphics representation is formed, for example, of an SVG (scalable vector graphic) representation of an animated vector graphic. When the vector graphics representation is compressed pursuant to compression operations of an embodiment of the present invention, a compact representation of the vector graphics is formed that is more compact than conventional frame-based compression schemes. The flexibility, the fully object-based structure, and the maturity of SVG is combined with a compact representation.
In another aspect of the present invention, a codebook is formed that includes codewords of the declarations, properties, attributes, etcetera, that define a vector graphic. Each codeword is a representation of a corresponding element of the vector graphic. The codewords of the codebook are substituted for the corresponding elements of the vector graphic, and a succession of codewords form the compressed form of the vector graphic. Other types of data are analogously also coded utilizing an appropriately-configured codebook. Groups of the data are coded according to codewords contained in the codebook to form the data in the compressed form. Once compressed, the data is communicated upon the communication channel.
In a further aspect of the present invention, a dynamic codebook is provided. A dynamic codebook is a codebook whose codewords, or the interpretations thereof, change over time. The changes are dependent, for instance, upon the context forming the data that is to be communicated. The change is alternately, or collectively, also dependent upon previously-signaled data, or based upon other indicia.
In another aspect of the present invention, the codebook forms a conversion algorithm whose execution compresses content prior to its communication upon a communication channel. The codebook at which the conversion algorithm is defined forms a dynamic codebook when the conversion algorithm is changeable. The conversion algorithm, or its interpretation, changes over time, depending, for instance, on the content or previously-signaled data.
In another aspect of the present invention, an encoder operates to access the codebook when content, which is to be communicated, is delivered to the encoder. The content provided to the encoder is segregated into groups. When the content forms a vector graphic, the groups of the data form keywords. The encoder detects successive keywords and encodes the successive keywords by substituting therefor codewords contained at, or derived from, the codebook. The encoded content, formed of the encoded keywords, or other groups of data, are compressed relative to the content prior to encoding.
In these and other aspects, therefore, apparatus, and an associated method, is provided for a communication system in which content is communicated by a sending station. The content is formed of groups of data items. The content is compressed into compressed form to facilitate communication thereof, in compressed form, upon a communication channel. At least a first sending-station codebook is positioned at the sending station. The sending-station codebook contains a conversion mechanism. The conversion mechanism defines a manner by which to compress the content. An encoder is coupled to the at least the first sending-station codebook. The encoder is further coupled to receive the content to be communicated by the sending station. The encoder encodes at least a first selected group of data items of the content by accessing the conversion mechanism and encoding the at least the first selected group of data items according to the conversion mechanism to form a coded representation thereof. The coded representation is of a smaller length than the first selected group of data items prior to encoding thereof.
A more complete appreciation of the present invention and the scope thereof can be obtained from the accompanying drawings that are briefly summarized below, the detailed description of the presently preferred embodiments of the invention, and the appended claims.